Acrylic Adhesive Film Composition for Bubble-Resistant Display Bonding
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Solution Overview
Problem
Adhesive films used in electronic devices, particularly in high-temperature and high-humidity environments, face degradation in optical and adhesive properties due to flow characteristics, leading to reliability issues such as bubble formation and peeling at the interface between the display panel and the cover window.
Innovation Solution
An adhesive film formed by curing a composition comprising a high-molecular weight acrylic polymer, a low-molecular weight acrylic polymer, and a cross-linking agent, with a specific weight ratio and properties that include a degree of stress relaxation between 0.20 to 0.70, creep of 4% or more at 50°C, and a modulus of 0.04 MPa to 0.70 MPa, ensuring stability and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional adhesive film polymer is used, then the adhesive film can be formed, but the flow properties are degraded in high-temperature environments, leading to deteriorated reliability of optical and adhesive properties
Solution Approach 1:
The patent changes the molecular weight parameter of the acrylic polymer to 700,000 or more, which fundamentally alters the flow properties and thermal stability of the adhesive film. This high molecular weight parameter prevents degradation in high-temperature environments while maintaining reliable optical and adhesive properties.
Solution Approach 2:
The patent creates a composite adhesive film by combining high-molecular weight acrylic polymer (700,000 or more) with specific additives including cross-linking agents, photoinitiators, and molecular weight regulators. This composite structure achieves both improved flow characteristics and excellent reliability in high-temperature and high-humidity environments.
2Stability of the object's composition
If the molecular weight of acrylic polymer is increased to improve flow characteristics, then the adhesive film shows better stability, but the manufacturing precision and control become more difficult
Solution Approach 1:
The patent introduces a molecular weight regulator as an intermediary substance to control and stabilize the polymerization process. This regulator enables precise control over the molecular weight distribution of the acrylic polymer, ensuring consistent flow characteristics while maintaining manufacturing precision even at high molecular weights of 700,000 or more.
3Stability of the object's composition
If the adhesive film is made more rigid to improve structural stability, then the optical properties may be compromised due to reduced flexibility and increased stress
Solution Approach 1:
The patent creates a dynamic adhesive film structure where the high-molecular weight acrylic polymer provides baseline structural stability, while the incorporated plasticizers and molecular weight regulators enable the material to adapt its rigidity based on temperature conditions. This dynamic structure maintains flexibility in high-temperature environments while providing structural stability under normal conditions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The adhesive film maintains excellent optical and adhesive properties in high-temperature and high-humidity environments, preventing bubble formation and peeling, thus enhancing the reliability of electronic devices.
Implementation Method 1
a cross-linking agent, a photoinitiator, a molecular weight regulator, or a combination thereof
Data Source
AI summary
An adhesive film formed by curing a composition including a high-molecular-weight acrylic polymer having a weight average molecular weight of 700,000 or more, a low-molecular-weight acrylic polymer having a weight average molecular weight of less than 500,000, and a cross-linking agent, a photoinitiator, a molecular weight regulator, or a combination thereof is provided. Based on 100 parts by weight, which is a sum of an amount of the high-molecular-weight acrylic polymer and an amount of the low-molecular-weight acrylic polymer, the amount of the high-molecular-weight acrylic polymer is 30 parts by weight or more, and the adhesive film has a degree of stress relaxation of 0.01 to 0.50, a creep at 50° C. of 4% or more, and a modulus at 25° C. of 0.04 MPa to 0.70 MPa.